Diversity and Metabolic Potential of the Dominant Culturable N2-Fixing and P-Solubilising Bacteria from Tea (Camellia sinensis L.) Rhizosphere

The purpose of this study was to investigate the diversity of cultivable N2-fixing and P-solubilizing bacteria originated from 167 rhizospheric acidic soils samples of tea. Based on the fatty acid methyl ester profiles, 34 bacterial genera were identified with a similarity index of >0.3, but 69.2% of the identified isolates belonged to five genera: Bacillus, Pseudomonas, Paenibacillus, Stenotrophomonas and Arthrobacter. Among the 263 bacterial strains, 213 strains exhibited N2-fixing activity and 159 were efficient in phosphate solubilisation; 134 strains were efficient in N2-fixation and P-solubilisation. Most of the N2-fixing and P-solubilizing bacteria isolated were Gram-positive (59.3 and 52.8%), and Gram-negative constituted only 40.7 and 47.2%. A total of 102 dominant strains were characterized by carbon sources using BIOLOGM GN2 and GP2 plates. B. pumilus, B. subtilis, B. licheniformis, B. laevolacticus, P. fluorescens, P. putida, S. maltophilia and B. megaterium were the most frequent P-solubilizing and N2-fixing species in the tea rhizosphere soils. Utilization of high variety of C-sources by the N2-fixing and P-solubilizing acid tolerant strains may play an important role in adapting to a variety of crop plants, and thus potentially beneficial to the growth of tea plants in that specific acidic ecosystem